May be
difficult to tighten the stomach because the body fat level required
to get flat abs is lower than you can sustain with your current lifestyle/schedule,
or the body fat level required is lower than is healthy for your body
to function.

If you
have localized fat around your belly button, your stomach can be made
flatter with simple, scarless liposuction.

If you
have relatively little excess skin but it does appear that you have
some muscle laxity may be useful skin tightening techniques.

The use
of various skin tightening techniques have included Velasmooth, Alma
Accent, Titan, and Thermage.

You may
want to look into one of these modalities to tighten the skin but
it is not likely you will see any significant improvement.

Muscle
repair can be done via limited incisions but should not be performed
if you are considering having more children.

Abdominal
core strengthening using a Pilates style regimen may be useful.